CN218020051U

CN218020051U - Pushing and pressing head for polytetrafluoroethylene pasty extrusion molding

Info

Publication number: CN218020051U
Application number: CN202221794806.9U
Authority: CN
Inventors: 胡珂; 陈越; 韩桂芳; 翟孟凡; 付师庆; 韩淑丽; 杨永华
Original assignee: Shandong Dongyue Polymer Material Co Ltd
Current assignee: Shandong Dongyue Polymer Material Co Ltd
Priority date: 2022-07-12
Filing date: 2022-07-12
Publication date: 2022-12-13
Anticipated expiration: 2032-07-12

Abstract

The utility model belongs to the technical field of macromolecular material processing is used, specificly relate to a pasty extrusion moulding of polytetrafluoroethylene is with bulldozing head. The pushing head for polytetrafluoroethylene paste extrusion molding is changed from the traditional pushing head, the pushing head in the extrusion process is not designed into an integral structure any more, but is innovatively designed into a pushing head consisting of a plurality of pushing shafts which are concentrically sleeved and pushing die heads connected with the pushing shafts, the pushing die heads are driven by the pushing shafts, so that the inner and outer multiple layers of pushing heads which are concentrically sleeved stop layer by layer from outside to inside in the pushing process, and finally a cone-shaped structure is formed, wherein the cone-shaped structure is adapted to a cone-shaped area of a die. Therefore, the problem that materials are remained because the traditional pushing head cannot enter the conical area of the neck ring die is solved, the materials can be extruded out of the extrusion port as far as possible, the waste of raw materials is reduced, the production cost is saved, and the economic benefit is remarkable.

Description

Pushing and pressing head for polytetrafluoroethylene paste extrusion molding

Technical Field

The utility model belongs to the technical field of macromolecular material processing is used, specificly relate to a pasty extrusion moulding of polytetrafluoroethylene is with bulldozing head.

Background

Polytetrafluoroethylene (PTFE), commonly known as "Plastic king", has excellent chemical resistance, high temperature resistance, low dielectric constant, incombustibility, weather resistance, low friction coefficient, non-tackiness, self-lubricity and other characteristics, and can be used as engineering plastics to be made into polytetrafluoroethylene tubes, rods, tapes, plates, films and other products. The method is generally applied to corrosion-resistant pipelines, containers, pumps, valves with higher performance requirements, raw materials for producing radars, high-frequency communication equipment and radio equipment, and the like. However, polytetrafluoroethylene is difficult to flow after melting and cannot be melt-extruded, and a processing method such as die sintering molding or paste extrusion molding is generally used.

Paste extrusion molding, which is a commonly used processing and molding method of dispersed PTFE, comprises the following steps: firstly, mixing dispersed resin sieved by a 20-30-mesh sieve with organic liquid to prepare a pasty mixture in a certain proportion; then prepressing the blank into a cylindrical blank, putting the cylindrical blank into a charging barrel of a pushing machine, heating, and pushing and forming by using a plunger; then preparing various plates, belts, films, fibers and the like after calendering, deoiling and stretching.

Since dispersed PTFE is easily fiberized, the pusher head as a whole during extrusion is generally designed with a pushing surface (material contact surface) in the shape of a spherical surface having a certain curvature, the curvature of which is fitted to the inner diameter of the cylinder portion of the barrel of the pusher, as shown in fig. 1. Although the advanced fibrosis of dispersed PTFE can be effectively avoided, the pushing head with the radian and the spherical surface cannot completely enter a die cone area in a barrel of the pushing machine at the final stage of extruding pasty polytetrafluoroethylene, so that a part of material is remained in the barrel and cannot be extruded, and only can be discarded, which undoubtedly causes serious waste of raw materials, and therefore, the problem of material residue in the current plunger pushing and forming process needs to be solved urgently.

SUMMERY OF THE UTILITY MODEL

The utility model discloses an aim at bulldozes the remaining problem of shaping in-process material to present plunger, bulldoze the head in extruding the technology and improve, change the tradition, the head that bulldozes in no longer will extruding the technology designs into an overall structure, but innovatively will bulldoze the head and design into to bulldoze the axle by the concentric looks cover of a plurality of and the consecutive die head that bulldozes and constitute, drive through bulldozing the axle and bulldoze the die head, make the concentric looks cover inside and outside multilayer bulldoze the head and stop pushing the in-process by outer to interior successive layer, finally form the cone structure, this cone structure suits with the bush toper district. Therefore, the problem that materials are remained because the traditional pushing head cannot enter the conical area of the neck ring die is solved, the materials can be extruded out of the extrusion port as far as possible, the waste of raw materials is reduced, the production cost is saved, and the economic benefit is remarkable.

The utility model discloses a concrete technical scheme as follows:

a pushing head for polytetrafluoroethylene paste extrusion molding comprises at least two pushing shafts which are concentrically sleeved with each other, wherein one ends of the pushing shafts are connected with pushing die heads which are also correspondingly concentrically sleeved with each other; the pushing shaft at the center and the pushing die heads connected with the pushing shaft are cylindrical, the layer-by-layer outer layer pushing shaft sleeved outside the central pushing shaft and the pushing die heads connected with the outer layer pushing shaft are cylindrical, and the outer diameter of each pushing die head is larger than that of the pushing shaft connected with the pushing shaft; the outer diameter of the pushing die head positioned in the center is larger than the inner diameter of the extrusion hole of the neck ring die, and the outer diameter of the pushing die head positioned on the outermost layer is equal to the inner diameter of the cylinder barrel of the pushing machine; in the two adjacent layers of pushing die heads which are concentrically sleeved, the inner diameter of the pushing die head positioned on the outer layer is equal to the outer diameter of the pushing die head positioned on the inner layer; each pushing and pressing die head is connected with a pressure sensor, the pressure sensor is connected with a pressure controller, and the pressure controller is connected with the corresponding pushing and pressing shaft.

Furthermore, the pushing shaft is in threaded connection with the pushing die head.

Further, the pushing die head located at the center is provided with an air exhausting device. Such as a vent hole in the upper end face of the push die.

Furthermore, all material contact surfaces of all the pushing die heads which are concentrically sleeved form a smooth spherical surface with the radian of 40-70 degrees together in the initial state. The design can facilitate the pushing head to better enter the cylinder barrel, and can also extrude a part of materials. The radian range can effectively avoid the influence on the product performance caused by the fact that materials at the edge part are subjected to more shearing force due to overlarge radian.

Further, the outer diameter of the pushing die head at the center is equal to the inner diameter of the joint of the lower port of the conical area of the die and the extrusion hole of the die.

Furthermore, the outer diameter of the pushing die head at the center is 10-15 mm larger than the inner diameter of the extruding hole of the die.

Furthermore, the radius of the pushing die head is 1-2 mm larger than that of the pushing shaft connected with the pushing die head.

Further, the stopping pressure set by the pressure controller is 3-5% higher than the yield point pressure of the extruded material.

Furthermore, the pushing shaft is made of stainless steel.

Furthermore, the pushing die head is made of polytetrafluoroethylene.

The beneficial effects of the utility model are that: paste extrusion moulding of polytetrafluoroethylene when carrying out the material and extruding with bulldozing the head, through the drive that pushes away the pressure axle, all concentric mutually the die head that bulldozes advances with same constant speed, get into the toper district after, outmost bulldozes the die head earlier with the contact of bush toper district inner wall, because of its external diameter equals the internal diameter that pushes away the press cylinder, consequently receive limiting displacement earliest, stop promptly and advance. At the same time, the inner layer pushing die head continues to advance until reaching the respective set position, namely, the inner layer pushing die head stops just after contacting with the inner wall of the conical zone. Therefore, the pushing die head stops layer by layer from outside to inside to finally form a conical structure, the conical structure is matched with the conical area of the die, the material is extruded from the extrusion opening as much as possible, and the material is prevented from remaining as much as possible. When the center-most pushing die head just contacts with the inner wall of the conical area and stops pushing, all the pushing heads return to the initial position together, and are folded and restored to form a spherical contact surface.

Each pushing and pressing die head is connected with a pressure sensor, the pressure sensor is connected with a pressure controller, and the pressure controller is connected with a corresponding pushing and pressing shaft. The pushing shaft of each layer can independently control the pushing die head connected with the pushing shaft to move forwards, stop at a set position and retreat.

In the adjacent two-layer pushing and pressing die heads which are concentrically sleeved, the inner diameter of the pushing and pressing die head which is positioned on the outer layer is equal to the outer diameter of the pushing and pressing die head which is positioned on the inner layer, so that the two-layer pushing and pressing die heads which are sleeved with each other can be tightly attached, and the problem that materials are left in gaps of the pushing and pressing die heads is avoided.

After the technical scheme is adopted, the raw materials in the conical area are extruded out as much as possible under the same process conditions, and the waste of the raw materials is reduced. And the performance of the extruded material is almost the same as that of the material extruded by the traditional die, so that the subsequent processing is not influenced, the production cost is obviously reduced, and the economic benefit is obvious.

Drawings

FIG. 1 is a schematic sectional view of a conventional PTFE paste extrusion pusher head.

Fig. 2 is a schematic cross-sectional view of a pushing head for polytetrafluoroethylene paste extrusion molding according to the present invention.

Fig. 3 is a front view of the pushing head of each layer in the pushing head for polytetrafluoroethylene paste extrusion molding according to the present invention.

Fig. 4 is a plan view of the pushing head for polytetrafluoroethylene paste extrusion molding according to the present invention.

The extrusion die comprises a central extrusion head 1, a central extrusion shaft 1-1, a central extrusion die head 1-2, a first outer layer extrusion head 2 from inside to outside, a first outer layer extrusion shaft from inside to outside 2-1, a first outer layer extrusion die head from inside to outside 2-2, a second outer layer extrusion die head from inside to outside 3-1, a second outer layer extrusion shaft from inside to outside 3-1, a second outer layer extrusion die head from inside to outside 3-2, a third outer layer extrusion head from inside to outside 4-1, a third outer layer extrusion shaft from inside to outside 4-1, a third outer layer extrusion die head from inside to outside 4-2, a cylinder barrel 5, a die cone area 6 and a die extrusion hole 7.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the accompanying drawings.

Take an extruder apparatus with a cylinder diameter of 100mm, a die outlet diameter of 10mm, and a die compression ratio of 100 as an example. As shown in fig. 2, comprises 4 groups of concentric pushing shafts, namely a pushing shaft 1-1, a first outer layer pushing shaft 2-1, a second outer layer pushing shaft 3-1 and a third outer layer pushing shaft 4-1 which are arranged at the center in sequence from inside to outside; the device also comprises a pushing and pressing die head connected with the corresponding pushing and pressing shaft, wherein the pushing and pressing die head 1-2, a first outer layer pushing and pressing die head 2-2, a second outer layer pushing and pressing die head 3-2 and a third outer layer pushing and pressing die head 4-2 are sequentially arranged at the center from inside to outside.

In the pushing shafts, the pushing shaft 1-1 at the center is of a solid cylindrical structure, and the first outer layer pushing shaft 2-1, the second outer layer pushing shaft 3-1 and the third outer layer pushing shaft 4-1 are of annular cylindrical structures sleeved layer by layer. The pushing die head 1-2 at the center is of a solid cylinder structure corresponding to the pushing heads connected with the pushing die head, the first outer layer pushing die head 2-2, the second outer layer pushing die head 3-2 and the third outer layer pushing die head 4-2 are of circular cylindrical structures corresponding to the various connected pushing heads. In the pushing process, the pushing shaft drives the pushing die head to stop layer by layer from outside to inside, and materials are extruded from the extrusion port as far as possible.

The pushing shafts are made of stainless steel materials, and the pushing shafts on each layer can be independently controlled.

The diameter of the pushing shaft 1-1 in the center is 21mm, the inner and outer diameters of the second outer layer pushing shaft 2-1 are 25mm and 46mm, the inner and outer diameters of the third outer layer pushing shaft 3-1 are 50mm and 71mm, the inner and outer diameters of the outermost layer pushing shaft 4-1 are 75mm and 90mm, and the gap between the two adjacent layers of pushing shafts is 2mm.

The pushing and pressing die head is made of white PTFE (polytetrafluoroethylene), the integral radian of the contact surface of the pushing and pressing die head and the material is 66 degrees, and the pushing and pressing die head and the material are respectively connected with a pressure sensor and can be fed back to a pressure controller through the pressure to control the pushing and pressing head to advance and stop.

The diameter of the pushing die head 1-2 at the center is 25mm, the inner and outer diameters of the pushing die head 2-2 at the second layer are 25mm and 50mm, the inner and outer diameters of the pushing die head 3-2 at the third layer are 50mm and 75mm, the inner and outer diameters of the pushing die head 4-2 at the outermost layer are 75mm and 100mm, and the diameter of the cylinder barrel is 100mm.

The stopping pressure set by all the pushing head pressure controllers is uniformly set to be 3% -5% higher than the yield point pressure of the extruded material of the traditional die.

The specific working principle is as follows: putting the preformed polytetrafluoroethylene blank into a cylinder 5 of a die cylinder body, starting a plunger extruder, driving a pushing head to descend at the same constant speed by all pushing shafts, applying pressure to the polytetrafluoroethylene blank, and extruding the material after the pressure is applied from a die extrusion hole 7 after the material passes through a die conical area 6. After the pushing die head enters the die head conical area 6, the outermost layer pushing die head 4-2 is firstly contacted with the inner wall of the die head conical area 6, and the outermost layer pushing die head 4-2 stops advancing under the limiting effect. At the same time, the inner layer pushers continue to advance until reaching the respective set positions (just in contact with the inner wall of the die cone 6) and stop. When the most central pushing die head 1-2 is just contacted with the inner wall of the die cone area 6 and the pushing is stopped, all the pushing heads are returned to the initial position together.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A pushing head for polytetrafluoroethylene pasty extrusion molding is characterized by comprising at least two pushing shafts which are concentrically sleeved with each other, wherein one ends of the pushing shafts are connected with pushing die heads which are also correspondingly and concentrically sleeved with each other; the pushing shaft at the center and the pushing die head connected with the pushing shaft are both cylindrical, the layer-by-layer outer layer pushing shaft sleeved outside the central pushing shaft and the pushing die head connected with the outer layer pushing shaft are both in a circular column shape, and the outer diameter of each pushing die head is larger than that of the pushing shaft connected with the pushing die head; the outer diameter of the pushing die head positioned in the center is larger than the inner diameter of the extrusion hole of the neck ring die, and the outer diameter of the pushing die head positioned on the outermost layer is equal to the inner diameter of the cylinder barrel of the pushing machine; in the two adjacent layers of pushing die heads which are concentrically sleeved, the inner diameter of the pushing die head positioned on the outer layer is equal to the outer diameter of the pushing die head positioned on the inner layer; each pushing and pressing die head is connected with a pressure sensor, the pressure sensor is connected with a pressure controller, and the pressure controller is connected with a corresponding pushing and pressing shaft.

2. The pushing ram for polytetrafluoroethylene paste extrusion molding according to claim 1, wherein said pushing shaft is screwed to said pushing ram.

3. A pushing head for polytetrafluoroethylene paste extrusion molding according to claim 1, wherein said centrally located pushing die is provided with a vent.

4. The pushing ram for polytetrafluoroethylene paste extrusion molding according to claim 1 wherein all the material contact surfaces of all the concentrically fitted pushing rams together form a smooth spherical surface having an arc of 40 ° to 70 ° in an initial state.

5. The pushing head for paste extrusion of polytetrafluoroethylene according to claim 1, wherein said pushing head has an outer diameter at the center equal to an inner diameter of a portion where the lower end of the tapered region of the die meets the extrusion hole of the die.

6. The pushing head for polytetrafluoroethylene paste extrusion molding according to claim 1, wherein said pushing head has a center-located outer diameter 10 to 15mm larger than an inner diameter of the die extrusion hole.

7. The pressing tip for polytetrafluoroethylene paste extrusion molding according to claim 1, wherein the radius of said pressing die is 1 to 2mm larger than the radius of a pressing shaft connected thereto.

8. The pushing head for polytetrafluoroethylene paste extrusion molding according to claim 1 wherein said pressure controller sets the stop pressure to be 3% to 5% higher than the yield point pressure of the extruded material.

9. The pushing tip for polytetrafluoroethylene paste extrusion molding according to claim 1, wherein said pushing shaft is made of stainless steel.

10. The pushing head for polytetrafluoroethylene paste extrusion molding according to claim 1, wherein said pushing die is made of polytetrafluoroethylene.